This invention relates to electrical articles made from metal powder compositions, as well as to methods for their manufacture.
Patterned metal articles, such as printed circuit boards, have many uses in the electronics industry. Printed circuits may be made by applying pressure with a heated die to metallic particles on an adhesive-coated substrate. Metal particles may also be mixed with a curable organic binder, and applied to a substrate using an adhesive layer, heat and pressure. Printed circuits may also be produced by embedding conductive granules mixed with an inorganic matrix material into a heat-softenable substrate. Silk screening methods may also be used to apply mixtures of organic materials and conductive particles to substrates, and compositions including metallo-organic compounds and metallic particles may also be silk screened on a substrate and heated to form a circuit pattern.
The adhesives and organic binders in these compositions are poor conductors of electricity, and, when mixed with metallic particles, reduce the overall conductivity of the resulting circuit patter. The use of inorganic and metallo-organic compounds is limited to specific combinations of materials and particular substrates, and requires high processing temperatures.
The invention provides an article comprising a conductive pattern on a substrate that forms all or part of one or more electrical components of an electromagnetic communication circuit, wherein the conductive pattern comprises a densified metal powder composition.
The invention provides an apparatus comprising at least one loop that forms an antenna to absorb and radiate energy and optionally at least one capacitor plate electrically coupled to the loop of the antenna to tune a resonant frequency of the antenna, wherein at least one of the antenna and the capacitor plate are defined by a conductive pattern of densified metal powder composition on a substrate.
The components of this invention may be combined with other components to form many functional articles, for example, radio frequency identification tags (also known as RFID inlays), RFID labels, resonant labels (also known as resonance labels), hardware components such as antennae, labels providing direct-contact connection to integrated circuits, tickets or cards which may optionally contain integrated circuits, batteries, fuses, displays, sensors and the like.
The invention also provides components of systems. For example, in a radio frequency identification system, the invention may provide an antenna coupled to a radio frequency identification reader proximate the storage area to produce an electromagnetic field and a radio frequency identification reader coupled to the antenna to power the antenna to communicate with the radio frequency identification tag. At least a portion of the radio frequency identification tag is defined by a conductive pattern of densified metal powder composition on a substrate. In another example, the invention may provide a resonant label, applied to or contained within the packaging of retail goods and used as part of a system to provide protection from theft in retail stores.
The invention makes it possible to produce a suitably conductive pattern on paper and other compressible substrates. These substrates are generally inexpensive materials and provide benefits to the final article such as, for example, flexibility, conformability, specific surface properties, and ease of recycling. The inventive method may be performed at low cost since it requires a minimum number of process steps and materials, does not require extreme, specialized or slow process steps, and minimizes process waste and pollution.
Examples of useful electrical components which may be made by this invention are electrical circuits, loop antennae (also known as coil antennae), dipole antennae, connectors, connector pads, capacitors, capacitor plates, bridges (also known as jumpers), resonant coils (also known as resonance coils), vias, resistors and electrical connections between these and other components.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.